The present invention relates to farm implements and, more particularly, to a seed metering assembly having individualized and independently controlled metering units for supplying granular material such as seed or fertilizer to a plurality of distribution headers.
Air seeders are commonly towed by tractors to apply seed, fertilizer, or micro-nutrients or any granular product to a field. For purposes of this application “seeding” shall include the application or deposition of any granular or particulate material onto a field, and “seed” shall include seed, fertilizer, micronutrients, or any other granular material that may be applied onto a planting surface, farm field, seedbed, and the like. It is generally advantageous to tow an air seeder in combination with a tilling implement, one behind the other, to place the seed and fertilizer under the surface of the soil. An air seeder has as its central component a wheeled seed cart which comprises one or more frame-mounted seed tanks for holding product, generally seed or fertilizer or both. Air seeders also generally include a volumetric metering system operable to measure a fixed volume of seed per unit of linear distance and a pneumatic distribution system for delivering the product from the tank to the soil.
The volumetric metering system is configured for distribution of product from the tank to the distribution headers of the seed tubes. The metering system typically includes a meter roller assembly employing augers or fluted cylinders (meter rollers) situated in a meter box assembly secured below the tank.
Typically the meter box will have a series of outlets known as runs that each leads to the distribution lines of the pneumatic distribution system. The pneumatic distribution system generally includes an air stream operable to carry product metered by the meter roller assembly through the distribution lines to a series of secondary distribution manifolds (“headers”), which in turn distribute product to a group of ground openers mounted on the seeding implement operable to place seed in the ground. The ground openers are configured to evenly deliver the product to the span of ground (the “seedbed”) acted upon by the seeding implement.
For most air seeders, the metering system mechanically separates the granular material into several runs; typically more than four runs, depending on the size of the seeding implement. As the size of seeding implements continue to increase as an effort to reduce seeding time and with the increasing costs of seed and fertilizer, it is increasingly desirable to stop the flow of granular material to one or more of the secondary headers, especially when the implement is passing over previously seeded or fertilized areas. Preventing the delivery of granular material to selected ones of the distribution runs is referred to as “sectional control” and is increasingly becoming an area of importance for air seeder design.
One proposed solution amounts to “starving” selected sections of the metering assembly. This is typically achieved by damning up the flow of granular material in the hopper so that the granular material is not presented to the meter roller assembly. One of the drawbacks of such a solution is that it is not uncommon for residual material to be against the meter roller assembly when the starving mechanisms, e.g., a gate or dam, are placed between the meter roller assembly and the hopper. As a result, there is a lag time between activation of the “starving” components and actual stoppage of seeding. This is particularly problematic for lightly seeded crops such canola in which it is possible for seeding to continue dozens of feet, e.g., 100 feet or more, after the “starving” components have been actuated.
Accordingly, there remains a desire for a seed metering assembly that provides effective sectional control.